Hypertrophic cardiomyopathy is characterized by a hypertrophic and non‐dilated left ventricle with disproportionate involvement of the intraventricular septum compared to the free walls, and by varying degrees of outflow obstruction during systole. Its symptoms and clinical course, pathogenesis and treatment are briefly discussed. It is speculated whether hypertrophic cardiomyopathy and hypertension are both caused by systemic disorders of calcium channels and calcium uptake and binding by cardiac and smooth muscle membranes, respectively.